A 7-month-old child whose first corneal transplant was unsuccessful underwent surgery Monday at the University of Rochester Eye Institute to implant an artificial cornea in an effort to give him sight. He is the youngest patient ever to receive the device.
Lukas Rakowsky of Dupont, Wash., was born in May with a tumor on his left eye. The tumor was successfully removed five weeks after his birth at Madigan Army Medical Center in Ft. Lewis, Wash. Lukas also underwent corneal transplant surgery that same day, in an attempt to help him achieve sight in the eye. The day after the surgery, though, Lukas' cornea began to cloud up again, signaling the transplant had been unsuccessful.
His parents, Shana and Peter Rakowsky, were referred to surgeon James Aquavella, M.D., at the University of Rochester Eye Institute. In addition to specializing in traditional cadaveric corneal transplants, Aquavella has been implanting plastic corneal devices since the 1960s. The first procedures were long and tedious, and results were not known for many months. Patients required careful follow-up for the rest of their lives in an attempt to reduce the ever-present danger of serious complications. But there have been great improvements over the past 40 years, he says, making possible new procedures like the one performed on young Lukas.
Aquavella began last spring implanting the AlphaCor, an artificial cornea that doesn't require donor tissue. The flexible, one-piece keratoprosthesis is designed to replace scarred or diseased corneas. The device is easier to implant than older models, cutting down on surgery time. The lack of donor tissue means the risk of rejection is eliminated. The new implant offers significantly more possibilities for patients at no more risk than implanting a cadaveric donor cornea, Aquavella says.
For patients like Lukas who have undergone unsuccessful corneal transplants and have little or no sight, this device can provide limited vision, allowing patients to see shadows, movement and colors, and some may even regain the ability to read.
"It is our expectation that for patients with a high risk of failure with a traditional corneal transplant, or as in the case of patients who have already failed previous attempts at corneal transplantation, this option offers renewed hope," Aquavella says. A similar device, the Dohlman KPro, also is increasingly employed in individuals with poor prognosis for a traditional cornea transplant, he adds.
The University of Rochester Eye Institute is one of 26 ophthalmic centers to evaluate the AlphaCor device. The Eye Institute is designated one of six centers of excellence in the United States to assist with the development of the technology. While the device has the approval of the FDA, Aquavella and colleagues are tracking complications, visual acuity, medications and failure rates.
Aquavella has implanted eight Argus implants to date. The majority of patients, all of whom have multiple eye diseases, have seen some improvement in their vision.
The surgery is similar to implanting a donor cornea. Part of the cornea is removed and the AlphaCor, about the size and thickness of a dime, is transplanted in its place. The procedure typically concludes with the formation of a flap of tissue from the conjunctiva (the white of the eye), which is used to cover the surface of the eye and create a natural bandage that allows the AlphaCor to heal in place.
Three months after surgery, a circle of tissue covering the front of the eye is removed, allowing light and images to enter. The patient sees through this opening, and the vision should be as good as the health of the back of the eye will allow. Some vision may be further improved with glasses or even with contact lenses fit over the prosthesis.
In the case of infants, such as Lukas, the conjunctiva can't be used since it is vital that light enter the eye as soon as possible to avoid amblyopia (lazy eye), which is caused by lack of visual stimulus to the brain early in a baby's life. Instead, the circle of tissue is removed when the device was implanted, and a transparent sheet made from amniotic membrane was used to protect Lukas' eye and allow light in.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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Ring the bells that still can ring. Forget your perfect offering. There is a crack, a crack in everything. That's how the light gets in.
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